Alloys and dentures made thereof



Patented May 2, 1950 The present invention relates -to alloys *an'd more particularly to alloysespecially suitabledor cast dentures and 'for -jewelry.

"-It has previously'been'proposed to provide =var- -ious types of alloys for -usefin placeof-gbldfor dentures *and for jewelryuse. In? general these alloys are of the chromium-cobalt nickel*type 'with irninor additionsof other mo'difying metals. Thistype alloy" has; proven" superior 'ror "many uses to the 5301a"Fpl'B7110111513 lisd but at 'the sametimesuilered from "several disadva-ntages. Among the "disadvantages 01'; ---alloysor -this type were their extremely high "melting pointsg great hardness,-"brittleness; etc. ,'I'he;hig-h mltingpoint madethemratheridiflloult for usein' dentalyarid other casting 'sincethemelting'point-was too high to permit-the use'iof thebrdinary calciumasulfate bonded investment-material. Useofthe'; alloys of this type therefore required-special investments and-special casting techniques. ""Iheir high' hard- *nessand fusion point also'required speciar techniques for soIderingandthe use :ofrspeeial hard solders.

Although attemptsihave been made '5 to lower the fusion point of the-chromium cobaltorichromium-cobalt-nickel type of alloy by the addition of -other--meta-ls; such as," for exampley-coppert or copper and 'ironfltheaddition of these metals .IOWGIStheSCOIIOSlOIITTGSIStaHCB of alloys of this type and also resulted in the production of more readily oxidizedzallloysiwliichiproduced undesirable roughcastings...

In accordance with the present -.;invention, however, the surprising discoveryhasrbeen made that when'goldis' added'in minor amount to alloysi'of the nickel-cobaltechromium type wesultant glloyhasza ieweredefusion' pointrgsdfiicient to enable its casting according to the conventional casting te'chniqueand also permitsthe .use or; the (conventions; ,tzcalciumcsuliate.ghoiided investment material. Although as is known in the antt-gold and alloys consisting prim rily f gold'are, "in some instances, less desirable'for dental use and other uses involving extreme corrosive conditions than the nickel-cobalt-chromium types because of the tendency of the gold to discolor in the presence of sulfides and other sulfur containing materials, it has been found in accordance with the present invention that alloys containing in addition to the base alloy of nickel,

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cobalt and *ohroi-nium, relatively-small amount of gold as, for example, of the order of 2%to 2 by Weight of thetotalaHoy, and preferably from-y5% to aby wei htt are not subject to discoloration 201"- attackeeyenein ".1hB-pI 8Se.ILQe:;,QI sulfides or sulfur. At the same time, the additionpf' the gold lowers the fusion point suiiifcientlv to permit casting" in' the calcium sulfate *-bonc;ledj-investment. Further; the new ailoys'ma-y ""beeasily' soldered; using the ordinary soft solders and-"methods ofthedental and jewelryart.

.:.Themew'alloys aresufficiently-ductile: sozfthat ethey: may bej adrawrn'zinto wire'land-atheygcombine ,uthiS high ductilitywwith "high resilience; and. imv -pactestrength. -Further, theymay be? machined and may arise a round .and zlmlishedon r ee grinders.

:The ;new:alloys 5h avemelting points which wary from approximately :.-1900.'F.. to 215.0 F. depend- :ing; upon the :amount :ofsgoldadded;- toithe. base :alloy, foniexamnle-"with the-addition of 5.%:-* old the fusion apoint :ofwthex alloy: :is approximately .1 end-with theaaddition' of 25% Qldz'the fusio po'nt islowered:tosapproximately1900?";F. E01 ordinary denturesitispreferable toutilize alloy containingbetween 5%: andx10% :of @goldaand for: more complicated dentures or. other articles which requirezbend-ingor'fitting. assmueh as to gold may beadded. Preferably aadditl-on lof beryllium -serves -to the base alloy to which'thego1d is added in the amounts hereinbefore. specified, consistsof 00 .40% nickel,;201% to,35 chromium andl'.20.% to 30% cobalt. "In addition to these metals from :0.I' t0 10% of molybdenum may be added, this i-addition' serving toimprove the fluidity of the tilloy fonmoresirrtrieate castings. Beryllium-may.

,iusion point andratcthe same. timehelps .;tO' inrease the. str n h-and hardness f theresultant pastings. .Preferably, in order to prevent extreme ab t ness -the --:Qa1t n .cQntentshQuId .bemaim tainediaslowras possible andin anyevent should not be allowed to exceed 0.8%. It is also to be understood that small amounts of other elements may be added if desired for conventional purposes such as the deoxidation of the melt, without affecting the desirable properties of these alloys.

The new alloys according to the present inven- I tion possess a pleasing platinum-like color and where the higher proportion of gold is used there is a slight yellowish tint.

The following examples serve to illustrate the alloys of the present invention but are not intended to limit the same:

Example I An alloy was prepared containing the following metals in the proportions specified by weight:

Per cent Nickel Approximately 35 Cobalt Approximately 25 Chromium Approximately 35 Gold Approximately The above alloy had a melting point in the An alloy was prepared containing the following metals in the proportions specified by weight: 7 Per cent Nickel A--. Approximately 30 Cobalt Approximately Chromium Approximately Gold Approximately 25 This alloy was softer than the alloy of Example I but still possessed a relatively high degree of hardness; The melting point of the alloy was approximately 1900 F. and the alloy'could be easily cast utilizing the ordinary calcium sulfate bonded investment materials. The alloy of this example had a' color with a slight-yellowish tint.

A denture was produced casting. The casting was smooth, more easily polished and could be more easily bent into various shapes as compared to the denture of Example I. It was smooth, less resistant to highly corrosive conditions and to tarnishing in the presence of sulfur and sulfides. The corrosion' resistance, however, was still quite marked and suitable under most conditions.

Example 'I I I platinum-like An alloy was prepared containing the following The above alloy had a meltin point in t e neighborhood of 2075" ER, and produced eXcellent dentures when melted and cast in the converf tional calcium sulfate bonded investment in accordance with dental casting technique.

The castings were of a platifrom this materialby parting 'from the therefore the invention is not limited to what The surface of the castings thus produced were smooth and require a minimum of further finish ing steps. The castings were of a platinumwhite color, were hard but resilient, and could be easily polished utilizing an ordinary lathe.

To any of the alloys of the above examples beryllium and molybedenum could be added in the amounts specified hereinbefore without changing the fusion point to any appreciable amount. The major effect on the fusion point being produced by the addition of gold. Beryllium andmolybdenum will, however, change the relative fluidity, castability, resilience, hardness and machinability and can be adjusted to confer the properties known in the art.

It would be obvious to those skilled in the art that various changes may be made without despirit of the invention and is described in the specification but only as in- ..dicated in the appended claims.

1 from 2% to 25% of gold.

What is claimed is:

1. An alloy consisting of a base alloy consisting of from 30% to 40% of nickel, from 20% to 35% of chromium and from 20% to 30% of cobalt, said base alloy being modified by the addition thereto of from 2% to 25% of gold.

2. An alloy consisting of a base alloy consisting of from 30% to 40% of nickel, from 20% to 35% of chromium and from 20% to 30% of cobalt, said base alloy being modified-by the addition thereto of *from 5% to 10% of gold.

3. An alloy'consisting-oi a base alloy consisting of from 30% to 40% of nickel, from 20% to 35% of chromium, from 20% 'to 30% of cobalt, and from 0.1% to 10% of molybdenum, said base alloy. being modified by the addition thereto of 4. An alloy consisting of a base alloy consisting of from 30% to 40% of nickel, from:20% to 35% of chromium,- from 20%. to 30% of cobalt, and from 0.1% to 5% of beryllium, said base alloybeing modified by the addition thereto of from 2% .to 25%of gold. 7 a

.5. An alloy consisting of a base alloy consisting of from 30% to 40% of nickel, from 20% to 35% of. chromium, from 20% to 30%. of cobalt, from 0.1% to 10% of molybdenum and from 0.1% to 5% of beryllium, said base alloy being modified by the addition thereto of from 2% to 25% of gold.

6. A denture formed of the alloy of claim 1.

7. A denture formed of the alloy of claim 2.

DALMAR A. TIFFT.

REFERENCES CITED The following references ,areof record in the file of thispatent:

UNITED STATES PATENTS Number Name 7 Date "404220 Osterman et al. May 28," 1869 V FOREIGN PATENTS 1 ,Number Country Date 18,212 Great Britain July 9, 1914 Of 1913 628,306

Germany Apr. 1, 1936 

1. AN ALLOY CONSISTING OF A BASE ALLOY CONSISTING OF FROM 30% TO 40% OF NICKEL, FROM 20% TO 35% OF CHROMIUM AND FROM 20% TO 30% OF COBALT, SAID BASE ALLOY BEING MODIFIED BY THE ADDITION THERETO OF FROM 2% TO 25% OF GOLD. 